Isoprene is a monomer raw material for synthetic polyisoprene, and is an important material, in particular, in the tire industry. In recent years, the technique for conversion from a production process of basic chemicals relying on petroleum to a production process from renewable resources such as plant resources has been developed and practical realization thereof is steadily progressing. Also regarding isoprene, for example, a production technique from saccharides as a raw material by recombinant Escherichia coli is known (Patent Documents 1 and 2).
Regarding the production process from renewable resources, most of the conventional techniques are production methods by microorganisms relying on organic substances, in particular, saccharides, glycerol or oil components, including the aforementioned isoprene production technique. However, for covering the global production quantity of a large number of basic chemicals derived from petroleum, the quantities of saccharides, glycerin and oil components derived from plant resources and the like that are currently available will be necessarily insufficient for carbon sources of microorganisms. In other words, the production quantity of basic chemicals by microorganisms relying on saccharides or oil components is limited also in the future. These processes also have a fear of competition with foods.
Syngas (synthesis gas) is a mixed gas mainly containing carbon monoxide, carbon dioxide, and hydrogen, which is efficiently obtained from waste, natural gas and coal by action of a metal catalyst under high temperature and high pressure. In the field of C1 chemistry by metal catalysts starting from syngas, a process for mass production of liquid chemicals such as methanol, formic acid and formaldehyde at low costs has been developed.
Carbon monoxide, carbon dioxide and hydrogen are contained in syngas derived from waste, industrial exhaust gas, natural gas or syngas derived from coal, and are available almost permanently. However, at present, examples of producing chemicals by microorganisms from C1 carbon sources represented by syngas are very limited. Only production of ethanol, 2,3-butanediol or the like from syngas is currently under development. In particular, there is little report about utilization of a syngas utilizing substance by a recombinant. Patent Document 3 discloses a production technique of isopropanol by a recombinant of Escherichia coli. In this technique, a plurality of CO metabolic enzyme genes are introduced into Escherichia coli to impart a syngas utilizing ability, and isopropanol is produced from syngas. However, this technique does not relate to production of isoprene.